1. Field of the Invention
The present invention relates to the field of surgery for the treatment of disorders which occur in the uterus of female mammals, especially humans. More specifically, the invention relates to a particular surgical process which utilizes a laser to treat the diseased tissue in the uterus and also to a fallopian tube ostial plug which is used in the surgical procedure.
2. Background Information
In the treatment of diseases of the uterus, particularly in the treatment of menorrhagia, it is desirable to destroy the endometrium. Menorrhagia is a condition which occurs in certain diseases, which affects the endometrial lining of the uterus. The condition results in excessive menstrual flow or bleeding. In the treatment of the uterus, particularly in the treatment of menorrhagia, it is desirable to destroy the endometrium by means of photocoagulation. Typically, a laser is used to cause the photocoagulation of the endometrium. After the endometrium has been destroyed by photocoagulation, the menorrhagia is sufficiently decreased or even eliminated without the necessity of resorting to a more drastic surgical procedure such as a hysterectomy.
The Nd:YAG laser is particularly well suited for permanent destruction or ablation of the endometrium by photocoagulation. The term Nd:YAG is an abbreviation for neodymium-yttrium aluminum garnet.
The Nd:YAG laser procedure is conducted hysteroscopically, i.e., is conducted with an hysteroscope so that the procedure can be visually observed. In Nd:YAG hysteroscopy, delivery is by flexible, coated, fiber optic cable with saline used for uterine distension. The entire endometrium is photocoagulated from each cornu down to the internal cervical canal. The fiber tip is placed just off the endometrial surface and moved outward concentrically. Firing the laser results in visible blanching of the endometrium with tissue destruction extending downward to a depth of about 3-4 millimeters which is deep enough to penetrate the basalis layer and enter the muscularis and thereby destroy the regenerating portion of the endometrium.
An important part of the procedure involves the flushing of the uterine cavity to provide distension and visibility during the process; to function as a heat sink to avoid overheating and to wash out any blood and debris produced by firing the laser. As a result of the use of saline in this manner, the procedure inherently exposes the patient to the risk of fluid absorption or even fluid overload since the saline can enter the body cavity via the fallopian tubes. The fluid overload may result in edema or swelling due to the body's absorption of the saline. Absorption of a sudden infusion of extravascular fluid is particularly troublesome in patients who are anemic or who have cardiac or renal disease since they are particularly sensitive to changes in body fluid levels and electrolyte balance. Thus, a desirable improvement in the area of intra-uterine hysteroscopic Nd:YAG laser procedures would involve the reduction or elimination of extravascular fluid absorption and the risk of fluid overload.
In all of the prior art methods for carrying out ablation of the endometrium with a Nd:YAG laser, it has been observed that a significant amount of saline vascular absorption occurs and in many cases there is clinical vascular fluid overload.
In a method described in a publication by Milton Goldrath et al, entitled "Laser Photovaporization of the Endometrium for the Treatment of Menorrhagia" (American Journal of Obstetrics and Gynecology; vol. 140; No. 1; May 1, 1981; pp 14-19) it was noted that patients who have undergone the laser photovaporization of the endometrium, have shown evidence of fluid overload. This occurred even though an additional surgical technique (laparoscopy) was used to apply a Yoon ring to the fallopian tubes to patients who have not had prior sterilization. Apparently, the laparoscopic application of a Yoon ring to the fallopian tubes failed to avoid fluid absorption and fluid overload since some patients showed clinical signs of fluid overload. In addition, the laparoscopic procedure required an incision and thereby subjects the patients to additional obvious risks. Thus, Goldrath's procedure exposes patients to the risks of fluid overload and additional risks due to the incision.
In a publication by James F. Daniell, entitled "Hysteroscopic Laser Surgery Breaks New Ground" (Contemporary OB/GYN Special Issue; Update on Surgery, 1985; pp 82-99) it is stressed that fluid overload is a genuine risk in hysteroscopic laser procedures performed in the uterus. It is not surprising, therefore, that current consent forms which are signed by patients who are about to undergo the Nd:YAG procedure, acknowledge their understanding that the patient may absorb some of the irrigating solution and become edemateous and require treatment with an intraveneously administered diuretic.
More recently, this procedure has also been described in an article by James Daniell et al entitled "Photodynamic Ablation of the Endometrium with the Nd:YAG Laser Hysteroscopically as a Treatment of Menorrhagia" (Colposcopy and Gynecologic Laser Surgery; vol. 2, No. 1; published by Mary Ann Libert, Inc.; 1986; pp 43-46). In this procedure it is also recognized that the Nd:YAG laser surgical procedure results in the risk of fluid absorption and fluid overload. It is stated by the authors that others, such as Goldrath, have reported fluid overload and, in their own experience, there was significant saline vascular absorption which ranged from 100-800 cc with an average of 300 cc being absorbed. It was also noted by Daniell, that in his procedure, the patients who were not previously sterilized were subjected to a laparoscopic tubal occlusion procedure prior to the hysteroscopic laser procedure, to assure that all the patients were sterilized. Thus, Daniell, like Goldrath, requires an incision due to the laparoscopic procedure. Daniell also observes a significant fluid absorption level.
Daniell et al also note that another surgeon (Lamano) has reported that the laser surgical procedure results in a large amount of fluid absorption (600-4800 cc). It was further reported that the large absorption was similar in patients who underwent a preliminary tubal ligation and in patients who did not undergo tubal occlusion.
It has been stressed by workers in this field that tubal occlusion was undertaken as a preliminary step in these laser operations, and FDA protocol required it to preclude the possibility of fertilization from occurring after the procedure was completed. Thus, it was not considered desirable to remove the tubal occlusion since such removal would enhance the risk of future fertilization which was to be avoided.
More recently, Daniell et al have found that achieving sterility by means of tubal occlusion is unnecessary as a prerequisite in the procedure. In fact, it has been recently concluded by Daniell that tubal sterilization should not be a prerequisite for performing the procedure because the laser procedure resulted in sterilization anyway. Thus, it would be unnecessary and unwise to subject a patient to a preliminary laparoscopic tubal occlusion procedure. In addition, tubal occlusion as practiced in the prior art did not minimize or eliminate fluid absorption since there was a significant amount of fluid absorption in patients who had a preliminary tubular occlusion as well as in those who did not have a preliminary tubal occlusion. Thus, Daniell et al have concluded that tubal sterilization should not be a prerequisite for performing endometrial ablation with a laser if the only reason for tubal occlusion was to reduce the risk of saline intravascular absorption.
It will thus be observed that the prior art teaches that either the preliminary tubal sterilization by means of tubal occlusion should not be reversed or, as later discovered, it should be avoided altogether.
An additional problem associated with Nd:YAG laser surgery, is the risk of infection, especially peritonitis, if fluid were to enter the body cavity through the fallopian tubes during the procedure. Thus, a procedure which minimizes or avoids passage of fluid through the fallopian tubes into the body cavity will minimize or avoid the risk of infection as well as the risk of fluid overload.
The individual skill of the surgeon is also a factor which contributes to the risk of fluid overload and infection. The longer it takes a surgeon to complete the procedure, the longer the patient will be subjected to the flow of saline into the uterus. Consequently, surgeons who are relatively inexperienced in conducting this surgery may be subjecting their patients to greater risk than surgeons who have perfected their technique since the more experienced surgeons can complete the procedure in a relatively shorter period of time. Even experienced surgeons may occasionally require additional time to complete the procedure because of complications which may occur while the surgery is in progress. Thus, it would be beneficial to be able to minimize the above mentioned risks when the surgery takes a longer period of time to photocoagulate the endometrium.